There are four basic
forms of volcanoes, shield volcanoes,
cinder cones, and strato
volcanoes. Shield volcanoes, like Kilauea, tend to bulge before an
eruption, and are shaped like an upturned warrior's shield. They are created
by basalt, a type of lava. Strato volcanoes
are more like cones, and are made out of thick viscous, pasty lava
and pyroclastics. Cinder cones
are like mini strato volcanoes, and are basically made by tephra
falls, or ash falls, and pyroclastics. The last one is the lava field.
A lava field is basically a flat field of lava.

Cinder Cones

Cinder cone volcanoes are
probably the most common volcano type. They usually aren't the central
vent of a volcano, but parisitic cones. Cinder cone eruptions are usually
violent, with thick, sluggish lavas. As the lava is hurled through the
air it cools, creating pyroclastics
and tephra. The pyroclastics form a
cone like vent.

Shield Volcanoes

Layers of basalt
lava make shield volcanoes.
The lava has a low level of silica, so it is not viscous. The lava instead
of piling up flows freely forming a sort of shield shaped volcano.
The top of shield volcanoes usually has a caldera,
or large crater. The magma chamber sometimes empties, and cannot support
the mountain above and it collapses, creating a caldera.

Strato Volcanoes

Strato volcanoes are made by
thick, sluggish, viscous, andecitic
lava, and rhyolithic lava. Its lava
dome builds up the volcano. During a violent eruption the entire mountain
could be entirely destroyed. During one such eruption, on Krakatoa, the
entire island the volcano was on was nearly blown away. During eruptions,
unlike shield volcanoes, the lava isn't as hot and looks more like chunky,
gray toothpaste. In some cases volcanoes can be a sort of mixture of volcanoes
or compound volcano. For instance
Vesuvius, in Italy, has a shield volcano on its side and the main volcano
is a strato volcano.

Lava Plains

Lava plains are basically just
flat fields of basaltic lava. Lava plains are the rarest volcanoes in the
world. Almost never there is tephra in a lava plains eruption.

Volcano Hazards

All volcanoes, dormant or active,
can pose danger. If there is an earthquake, there could be a landslide,
and the heat of the magma underneath the volcano could melt ice and trigger
a mud flow, or lahar. A lava dome may
even collapse creating a nuees ardentes.
During an eruption there can be the above plus ash falls, lava flows, and
rock bombs.

Different Types of Eruptions

There are basically four types
of volcanic eruptions, Hawaiian, Strombolian,
Vulcanian, and Plinian.
Hawaiian eruptions are usually quiet, and non explosive. Strombolian eruptions
include pockets of gas that explode when they reach the surface. In Vulcanian
eruptions the lava is as thick as tar and is almost always incredibly violent.
The most violent of all, Plinian eruptions include large pyroclastic
flows, nuees ardentes and
almost no quiet lava.

Types of Lava

There are four basic types of
lava, rhyolite, dacite,
andesite, and basalt.
In all magmas there is the mineral silica,
a substance that makes the magma sticky and slow moving. Basalt has the
least amount of silica, and flows the fastest of all magmas. It is 53%
silica. Then comes andesite, which is 63% silica. Dacite is 68%, and rhyolite
is about 75% silica.